package HomeWork.Demo04;

import java.util.Random;

public class YanZhengMa {
    public static void main(String[] args) {
        StringBuilder stringBuilder=new StringBuilder("");
        for(char i='a';i<='z';i++){
            stringBuilder.append(i);
        }
        for(char i='A';i<='Z';i++){
            stringBuilder.append(i);
        }
        for(int i=0;i<=10;i++){
            stringBuilder.append(i);
        }

        Random random=new Random();
        String Y="";
        for(int i=0;i<4;i++){
            Y+=stringBuilder.charAt(random.nextInt(0,stringBuilder.length()));
        }
        System.out.println(Y);
    }
}
